The transitional epithelium lining mammalian urinary bladder is particularly susceptible to chemical carcinogenesis. The morphological development of cancer in this tissue has been studied intensively. However, because of the small amounts of epithelial tissue available from bladders it has been difficult to examine the regulation of metabolism and growth in either the normal or the neoplastic state. The development of methods for organ culture of normal rabbit transitional epithelium, as well as the culturing of a spontaneously transformed derivative has allowed studies concerning cyclic AMP metabolism and hormonal regulation in these cells to be proposed. These studies are being carried out in order to test the hypotheses that the alterations in structure, growth, and function of transformed transitional epithelium may be related to changes in the metabolism of cyclic AMP and consequently its relationship to hormonal regulation. This hypothesis will be tested by examining the effects of hormones on cyclic AMP metabolism in cultures of isolated normal transitional epithelium and in cultures of the transformed epithelial cells. The properties, hormonal sensitivities, and subcellular localization of the enzymes of cyclic AMP metabolism (adenylate cyclase, cyclic nucleotide phosphodiesterase, and protein kinase) will be compared in the normal and transformed cells in an effort to uncover lesions associated with the neoplastic state. In addition, chronic experimental manipulation of cyclic AMP levels with agonists of adenylate cyclase and antagonists of phosphodiesterase will be performed in order to ascertain the effects of cyclic AMP upon the growth, morphology and regulatory mechanism of the transformed cells. This project will contribute to an appreciation of the physiological and biochemical changes that occur with neoplasia of the transitional epithelium, and may prove valuable to future developments in the area of pharmacological therapy of bladder cancer.